Maybe we'll get two.
Like, the 3.0 weapon not replacing Zodiac, but something alongside it. So those of us with zodiac zeta can use that to continue to grow that weapon, as well as a new quest for a 3.0 one. And anyone without a Zodiac can still do the quest, albeit at an increased rate up to Zeta, and then do that too.
Kinda like Relic and Mythic from XI.